The present invention relates to a method and apparatus for the manufacture of a photonic crystal element.
The photonic crystal element is an artificial crystal in which two kinds of media of vastly different refractive indices (dielectric constants) are arranged regularly with a period of the order of light wavelength. Conventionally, the photonic crystal element of such a structure is manufactured using an apparatus of such a construction as depicted in FIG. 1.
The apparatus of FIG. 1 is designed to orient dielectric fine particles 13 two or three-dimensionally in a container 12 placed on an XY stage 11. A spray source 15 is driven and controlled so that fine particles 13 contained in a powder container 14 are jetted out, for example, one by one from a jet nozzle 16, while at the same time the XY stage 11 is driven to orient the fine particles 13 in a desired pattern.
In this example, the jet nozzle 15 is mounted on a Z stage 17 in a manner to be movable in a Z direction (in the vertical direction). Reference numeral 18 denotes a DC servomotor for driving the Z stage 17. The spray source 15, the DC servomotor 18 and a DC servomotor (not shown) for driving the XY stage 11 are driven and controlled by a controller 19.
With the conventional photonic crystal element manufacturing method using the above-described apparatus, it is necessary, for the emergence of a photonic band gap in the light wavelength band, to arrange the fine particles on the order of light wavelength (submicron to several microns); that is, the jet of the fine particles and the XY stage need to be controlled with such an extremely high degree of accuracy.
Since such control presents serious difficulties, however, the manufacture of the photonic crystal element is not easy; in particular, much difficulties are encountered in manufacturing the photonic crystal element as intended.
In U.S. Pat. No. 5,651,818 there is disclosed a method of preparation of a photonic crystal element from a composite material. According to this conventional method, the photonic crystal element is fabricated by impregnating a reticulated mesh formed in a metal column of a high-melting point such as tungsten (W), by capillary action, with liquid material of a melting point lower than that of the metal column, such as aluminum oxide, and dissolving the metal column after the liquid material solidifies. With this method, however, it is difficult to form the photonic crystal element with reticulated mesh spacing held uniform in the entire body of the photonic crystal element on the order of light wavelength.
It is therefore an object of the present invention to provide a method that permits easy orientation of fine particles and hence facilitates the manufacture of photonic crystal elements, and an apparatus that implements the method.
The photonic crystal element manufacturing method according to the present invention comprises the steps of: orienting and dispersing fine particles in a polymer medium to obtain a composite material; and performing high-density compression molding of the composite material to compress it to such a size that a photonic band gap emerges, thereby obtaining a photonic crystal element.
In the above method, the high-density compression molding of the composite material is carried out by isostatic press through a pressure medium.
In the above method, the composite material is heated at the time of its high-density compression molding.
In the method, the fine particles are magnetic fine particles and an electromagnetic field is applied to the composite material at either one or both of the times of orientation and dispersion or high-density compression molding.
The apparatus according to the present invention for manufacturing a photonic crystal element from a composite material with magnetic fine particles oriented and dispersed in a polymer medium, comprises: means for applying an isostatic pressure to said composite material; means for heating said composite material; and means for applying an electromagnetic field to said composite material.